Cathode-ray type selector switch circuit



Nov. 4, 195 J. L. H. JONKER ET AL CATHODE-RAY TYPE SELECTOR SWITCH CIRCUIT Filed Feb. 15, 1949 INVENTORS. JOHANLODEMCIKHHYDBK Jomzz BY WILLHMIX fl W Pat ented Nov. 4, 1 952 CATHODE-RAY TYPE SELECTOR SWITCH CIRCUIT Johan Lodewijk Hendrik J onker and Willem Six, Eindhoven, Netherlands, assignors to Hartford National Bank and Trust Company, Hartford,

Conn., as trustee Application February 15, 1949, Serial No. 76,463 In the Netherlands April 20, 1948 4 Claims.

This invention relates to circuit-arrangements for automatic signal systems, for example telephone systems, for selecting one out of those of a number of lines of which the individual contacts provided in a test switch exhibit a potential which differs from the potential of the contacts of the other lines.

The circuit-arrangement according to the invention exhibits the characteristic that the test switch is realised in the form of a cathode-ray tube in which the individual contacts are provided as collecting electrodes for the cathode-ray beam, the deflection plates being supplied with'a step-like deflection voltage derived from a generator governed by a control voltage, a further electrode fed across a resistance being arranged in the cathode-ray tube in such manner that, when under control of the deflection voltage the cathode-ray beam impinges upon a collecting electrode associated with one of the desired lines, the said resistance has a variation in Voltage set up across it by means of which the supply of the control voltage for the generator producing the step-like voltage is interrupted.

The circuit-arrangement according to the invention and further embodiments thereof will now be described more fully by reference to the accompanying drawing wherein the sole figure is a schematic diagram of test apparatus in accordance with the invention for selecting a free line from a plurality of lines in an automatic signalling system.

The test switch is constituted by the cathoderay tube I (shown only diagrammatically) comprising a cathode 2, means (not shown) for gen-- erating the cathode-ray beam, deflection elec' trodes 3, 4 and a number of collecting electrodes 5 to 9 inclusive. The collecting electrodes are each associated with one line and constitute the individual contacts of the test switch.

The deflection plates are supplied with a steplike voltage originating from a generator which will be described more fully hereinafter and which is governed by a control voltage.

The cathode-ray beam is directed successively towardsthe collecting electrodes 5 to 9 inclusive by the action of the step-like voltage. The collecting electrodes and the cathode are separated by a further electrode, here a gridlike electrode Ill, which is connected by way of a resistance II to the positive terminal of the source of supply.

The collectingelectrodes 5 m9 inclusive are likewise connected in a manner not shown through the corresponding lines to a positive voltage, but if one line is occupied, the electrode associated therewith is connected to earth potential.

If, for example, the lines corresponding to the collecting electrodes 5 and 6 are occupied and the other lines are free, the collecting electrodes 5- and 6 exhibit earth potential and the other electrodes a positive potential.

The selection of a free line is effected in the following manner.

If, under the action of the step-like deflection voltage, the cathode-ray beam is first directed towards the electrode 5, most electrons of the beam will travel towards the grid-like electrode II! which exhibits a positive potential, so that resistance I I is traversed by a fairly considerable current and the extremity I2 of the said resistance acquires a comparatively low potential.

Under the action of the control voltage, the deflection voltage is increased by one step, whereaiter the beam is directed towards the electrode 5. Since the corresponding line is also occupied, the potential at point I2 is not varied so that the step-like voltage is again increased by one step under the action of the control voltage.

Now, the beam is directed towards the electrode I which exhibits a positive potential, re-

sulting in current distribution between the electrode 'I and the electrode Ill and hence in an increase in potential at point I2. As will be described more fully hereinafter, the supply of control voltage to the generator producing the step-like voltage is interrupted by means of the said increase in potential so that the deflection voltage is not increased further and the beam remains directed towards the electrode 7.

The step-like voltage is derived from a second cathode-ray tube system I3, comprising a cathode I l, means (not shown) for generatin a cathode-ray beam, deflection plates I5, I6, and two collecting electrodes II, I8. The collecting electrode I7 is arranged between the electrode I8 and the cathode l4 and is provided with apertures I9 in such manner that the beam strikes alternately the electrodes I3 and I9 during deflection.

The electrode I8 is connected by way of a resistance 2D to the positive terminal of the source of supply, the electrode I8 also being coupled directly to the deflection plate I5.

As has been explained in the prior patent application Serial No. 790,874, filed December 10, 1947 of the applicant, the current distribution between the electrodes I1 and I8 and the cousewers pling between the collecting electrode [8 and the deflection plate l5 result in a number of stable adjustments being obtained for the cathode-ray beam.

Under the action of a control voltage supplied to the deflection system, the cathode-ray beam may be moved from one stable position into an other stable position, the voltage between the deflection plates varying from position to position in a stepwise manner.

If now, the deflection plates l and I6 of the test switch I and the cathode-ray tube [3 are connected to a fixed potential, while the plates 3 and !5 are connected to one another, the potential of plate 3 will vary in a step-wise manner due to the variation in potential of plate I 5.

It is evident, that the cathode-ray tube systems I and it may be housed in one cathode-ray tube having a common cathode and deflection system. If, now, the cathode ray beam in this case exhibits the shape of a flat beam, 2. portion thereof may co-operate with an electrode system corresponding to the electrodes ill and it by which the position of the beam is determined, a further portion of the beam which is not collooted by this electrode system co-operating with a system corresponding to that of the tube 2, so that at any position this portion of the beam is directed towards one of the electrodes 5 to 9 inclusive.

The supply of control voltage to the deflection plate E5 of the cathode-ray tube i3 is controlled under the action of the potential of the extrernity it of resistance l i with the use of the following arrangement.

This arrangement comprises a combination oi two relays 2i and 22, each relay comprising two collecting electrodes housed in a cathode-ray tube and jointly constituting a switching path. Thus, the relay 25 is constituted by a cathoderay tube system having collecting electrodes 23 and 2t, deflection plates 25 and means for generating a cathode-ray beam, and a cathode 27. The collecting electrode 23 is of the secondary-emission type, fulfills the function of an auxiliary cathode and is fed with voltage by way of a potentiometer comprising resistances 28 and 29. The collecting electrode 24 is active as an ordinary collecting electrode and is connected to the positive terminal of the source of supply by way of a resistance 30.

If the resistances 28 and 29 are, for example, of equal value, the auxiliary cathode is connected to half the battery voltage and the anode 24 to the full battery voltage as long as the cathode-ray beam is not directed towards the auxiliary cathode 23. The switching path formed by the electrodes 23 and 24 is then open.

If the cathode-ray beam is directed towards the auxiliary cathode 23 by means of the deflection plates 2-5 and 26, secondary electrons will travel towards the anode 2 Consequently, the voltage of the auxiliary cathode 23 increases up to a, value slightly smaller than that of the g r ie 24. The switching path is then closed.

Theqlay 22 also comprises a collecting electrode 3! which is active as an auxiliary cathode, and an electrode 32 which is active as an anode. The collecting electrode 32 derives its potential from that of the auxiliary cathode 23 and this potential will thus increase if the switching path of relay 2! is closed. The auxiliary cathode 3! is supplied by way of a potentiometer 33, 3E and upon incidence of the cathode-ray beam and with closed switching path of the relay 2! it will ac- 4 quire a potential which, as before, is substantially equal to that of the anode 32.

Consequently, closure of the two switching paths results in the voltage at the auxiliary cathode 3i varying from, for example, halfthe battery voltage to substantially the full battery voltage. For a detailed explanation of the operation of this circuit-arrangement we may otherwise refer to the prior patent application Serial No. 13,996, filed March 10, 1948 of the applicant. which also provides means by which the operation of the tube may still be improved.

In the circuit-arrangcment under consideration the deflection plate 25 of relay 25 is connectcd to a fixed potential, the voltage of the plate 25 being derived from the auxiliary cathode 3i of relay 22. The fixed bias voltage is chosen to be such that with an open switching path of the relay 22, the beam from relay 2! does not impinge on the auxiliary cathode 23, which is the case with a closed switching path 22 if a higher potential is set up at the auxiliary cathode 3!.

The deflection plate 35 of relay 22 likewise connected to a fixed potential, the deflection plate 35 being connected to the extremity it of resistance H. The fixed potential chosen to be such that the beam strikes the auxiliary cathode 31 as long as the high voltage loss corresponding to occupied lines is produced across resistance ii.

The anode i i of the relay 2| may be connected, with the use of a changing contact 3?, either to the auxiliary cathode 23,, or by way of a condenser 33 to the source of control voltage, for example a pulse generator 39.

The operation of the arrangement is the following:

Assuming that at the-rest position the cathoderay beam of the test switch I is at the extreme left-hand side and strikes the collecting elec trode it, a low voltage prevails at the point it of resistance H and the cathode ray beam of relay 22 impinges upon the auxiliary cathode 3:, whereas the beam from relay 2| does not impinge on the auxiliary cathode 23. If the changing contact 37 is reversed, the switching path of relay 2! is short-circuited, which results in an increase of voltage at the auxiliary cathode 23 and hence at the anode 32. Since the beam from relay 22 is incident on the auxiliary cathode 3 i, the potential of the auxiliary cathode and hence the potential at the deflection plate 25 increases, so that the beam from relay 25 is incident upon the auxiliary cathode 23. Both switching paths are then closed. If, now, the changing contact 3"! is again reversed into the position shown, the relay 2! maintains itself andthe variations in voltage of the anode '24 brought about by the controlvoltage generator 39 are passed to the auxiliary cathode 3! of relay 22. The variations in voltage set up at the auxiliary cathode are transmitted by way of a blocking condenser 43 to the deflection plate i5 of the cathode-ray tube it. With each voltage pulse the beam of this tube moved on one step, which results in the voltage at the deflection plate l5 and hence at the deflection plate 30f tube 1 being increased by a determined value. Consequently, the beam of. tube 1 is directed towards the successive collecting electrode 5 to 9 inclusive.

If the collecting electrode exhibits a positiv potential, current distribution takes place between the electrode i and iii and the current flowing to the electrode I 6 decreases, resulting in an increase in potential at point I2.

The beamirom relay 22thus leaves the auxiliary cathode 3| and the voltage thereof decreases. This also results in a decrease in potential of the deflection plate 25 of relay 2I, so that this relay is also deenergised and controlvoltage is no longer transmitted with the result that the beam of tube I3 remains in a stable position. The potential at the deflection plate I5 remains constant, so that the beam of tube I also remains directed towards the collecting electrode I.

The output circuit of each collecting electrode of tube I includes the energising circuit of a relay preferably operating by electronic means. Thus, the output circuit of the electrode 1 comprises the energising circuit M of a relay having a contact 42.

Owing to the incidence of the beam upon the collecting electrode 1, the relay is energised and th collecting electrode is connected via the contact 42 to earth. The current of the beam subsequently flows to the collecting electrode I0 with the result that the voltage at point I2 decreases and the cathode-ray beam from relay 22 is again incident upon the auxiliary cathode 3|. How- 'ever, since the anode 32 of this relay only exhibits a potential determined by the potentiometer ratio 28, 29 there will be no increase in voltage of the auxiliary cathode 32 and hence of the deflection plate 25. Consequently, the cathoderay beam from relay 2| is not incident on the auxiliary cathode 23 and control pulses are not passed, so that the beam of the test switch I remains directed towards the electrode I.

However, the arrangement is ready for selecting a further free line and is put into operation by reversing the changing contact 31.

It may still be mentioned that the switch I, after the last contact 9 has been scanned, may be restored to its initial position with the use of the cathode-ray tube system I3 in various ways as described in the prior patent application Serial No. 790,874.

It is alternatively possible for the beam of the test switch I, after the latter having been occupied, to be moved from the electrode 1 back to the initial position, which may be effected, for example, by temporary suppression of the beam from cathode-ray tube I3, so that this beam and hence also that of the switch I return to their rest positions.

What we claim is:

1. In an automatic signalling system provided with a plurality of line in which the free lines have a diflerent potential thereon than the busy lines, test apparatus for selecting one of said free lines comprising a cathode ray beam tube including in an evacuated envelope a beam source, a like plurality of spaced collecting electrodes, means to deflect said beam across said electrodes and a screen element interposed between said source and said electrodes, means connecting each of said electrodes to a respective line to impose the potentials of the lines on the associated electrodes, a resistance, means to impose a constant potential on said screen element through said resistance, a control voltage source, means responsive to said control voltage to apply a sweep voltage on said deflecting means varying in a stepwise manner to deflect said beam successively across said electrodes whereby an output voltage is developed across said resistance whose magnitude depends on the line potential on the electrode on which said beam impinges, and means coupled to said resistance and responsive to the magnitude of said output voltage corresponding 6 to the potential of a free line to interrupt said control voltage from said source thereof and thereby maintain said beam on an electrode connected to a free line.

2. An arrangement, as set forth in claim 1, further including a plurality of relays each interposed between an electrode and a line and being energized when the cathode ray beam is maintained at the associated electrode, said relay when energized actuating a switch connecting the associated electrode to a point having a potential at variance with the free line potential.

3. In an automatic signalling system provided with a plurality of lines in which the free lines have a higher positive potential thereon than the busy lines, test apparatus for selecting one of said free lines comprising a cathode ray tube including in an evacuated envelope a beam source, a like plurality of spaced collecting electrodes, deflecting plates to deflect said beam across said electrodes and a screen element interposed between said source and said electrodes, means connecting each of said electrodes to a respective line to impress the potentials of the lines on the associated electrodes, a resistance, means to impose a constant positive potential on said screen element through said resistance, a control voltage source, a generator responsive to said control voltage and coupled to said deflecting plates, to apply a sweep voltage thereto varying in a stepwise manner to deflect said beam successively across said electrodes whereby an output voltage is developed across said resistance whose magnitude depends on the line potential on the electrode on which the beam impinges, and means coupled to said resistance and responsive to the magnitude of output voltage corresponding to the free line potential to interrupt said control voltage from the source thereof.

4. Apparatus, as set forth in claim 3, wherein said generator comprises a cathode ray device including a beam source, a pair of deflecting elements and first and second collecting electrodes disposed at spaced positions normal to the incidence of said beam, said first collecting electrode being constituted by a plurality of spaced sections, a resistance, means to apply a direct potential to said first electrode and through said resistance to said second first electrode, means connecting said second electrode to one of said deflecting elements, means to apply a constant potential to the other of said deflecting elements, and means to apply said control voltage to said one of said deflecting elements.

J OI-IAN LODEWIJ K HENDRIK J ONKER. WILLEM SIX.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,110,548 Finch Mar. 8, 1938 2,122,102 Lundell June 28, 1938 2,204,055 Skellett June 11, 1940 2,301,748 Renshaw Nov. 10, 1942 2,339,684 Deakin Jan. 18, 1944 2,369,749 Nagy Feb. 20, 1945 2,387,018 Hartley Oct. 16, 1945 2,395,299 Skellett Feb. 19, 1946 2,483,450 Clark Oct. 4, 1949 2,492,346 Arditi Dec. 27, 1949 2,553,605 Ransom May 22, 1951 

